Position detection device and vehicle steering device

Abstract

A position detection device is configured to detect a position of a moving member moving backward and forward in a predetermined moving direction. The position detection device is provided with a conductive detection member attached to the moving member, and an exciting coil and a detection coil that are arranged extending in the moving direction of the moving member and facing the conductive detection member. The conductive detection member includes a recessed portion recessed in a direction away from the exciting coil and the detection coil. A voltage is induced in the detection coil by a current flowing in the conductive detection member due to a magnetic field generated by the exciting coil, and a magnitude of the voltage induced in the detection coil varies with a position of the recessed portion relative to the detection coil. A vehicle steering device is provided with a shaft, a housing, and the position detection device.

The invention claimed is: 
     
         1 . A position detection device configured to detect a position of a moving member moving backward and forward in a predetermined moving direction, comprising:
 a conductive detection member attached to the moving member; and   an exciting coil and a detection coil that are arranged extending in the moving direction of the moving member and facing the conductive detection member,   wherein the conductive detection member includes a recessed portion recessed in a direction away from the exciting coil and the detection coil,   wherein a voltage is induced in the detection coil by a current flowing in the conductive detection member due to a magnetic field generated by the exciting coil,   and wherein a magnitude of the voltage induced in the detection coil varies with a position of the recessed portion relative to the detection coil.   
     
     
         2 . The position detection device, according to  claim 1 , wherein the exciting coil and the detection coil are formed on a single substrate, and wherein the conductive detection member includes a facing surface facing the substrate through an air gap of a predetermined width, the facing surface is a plane parallel to the substrate, and the recessed portion is recessed in a direction perpendicular to the facing surface. 
     
     
         3 . The position detection device, according to  claim 1 , wherein the detection coil includes a pair of coil elements whose output voltage changes according to the position of the moving member, and a phase of the output voltage of each of the pair of coil elements during movement of the moving member is different from each other. 
     
     
         4 . The position detection device, according to  claim 3 , wherein each of the pair of coil elements comprises a combination of two sinusoidal-shaped conductor wires symmetrical across a symmetry axis line parallel to the moving direction, and the output voltage varies according to the position of the moving member by a difference between a strength of the magnetic field in a portion facing the recessed portion and a strength of the magnetic field in a portion not facing the recessed portion. 
     
     
         5 . The position detection device, according to  claim 1 , wherein the detection coil comprises a plurality of detection coils being aligned in a direction perpendicular to an extending direction of the exciting coil,
 wherein the conductive detection member includes a plurality of the recessed portions corresponding to the plurality of detection coils respectively at different positions in the moving direction, and   wherein a detectable range in which the position of the moving member can be detected by each of the plurality of detection coils is offset in the moving direction of the moving member.   
     
     
         6 . The position detection device, according to  claim 5 , wherein the plurality of the detection coils includes a first detection coil and a second detection coil, and
 wherein a detectable range of the first detection coil and a detectable range of the second detection coil overlap in part and are continuous in the moving direction.   
     
     
         7 . The position detection device, according to  claim 6 , wherein each of the first detection coil and the second detection coil faces the plurality of the recessed portions spaced apart in the moving direction while the moving member moves from one moving end to an other moving end in the moving direction. 
     
     
         8 . The position detection device, according to  claim 7 , wherein lengths in the moving direction of the plurality of the recessed portions facing the first detection coil are different from each other while the moving member moves from the one moving end to the other moving end, and wherein lengths in the moving direction of the plurality of the recessed portions facing the second detection coil are different from each other while the moving member moves from the one moving end to the other moving end. 
     
     
         9 . The position detection device, according to  claim 5 , wherein the recessed portions penetrate through the conductive detection member in a direction away from the exciting coil and the detection coil. 
     
     
         10 . A vehicle steering device, comprising:
 a shaft that moves axially forward and backward along a vehicle width direction;   a housing that houses the shaft; and   a position detection device that detects a position of the shaft relative to the housing,   wherein a wheel is steered by axial movement of the shaft,   wherein the position detection device comprises:   a conductive detection member attached to the shaft; and   an exciting coil and a detection coil that are arranged extending in a moving direction of the shaft and facing the conductive detection member,   wherein the conductive detection member includes a recessed portion recessed in a direction away from the exciting coil and the detection coil,   wherein a voltage is induced in the detection coil by a current flowing in the conductive detection member due to a magnetic field generated by the exciting coil,   and wherein a magnitude of the voltage induced in the detection coil varies with a position of the recessed portion relative to the detection coil.